[JDWalton]

Most codes are from intakes that have a different MAF size. Like the BBK for example is the factory size inlet, so it doesnt need a tune because for the velocity the air is moving through the MAF, the same amount of air is still reaching the engine, so the factory tune is still good. Your power gain is simply due to less resistance in the filter.

Now take like a Steeda or any of the others with a 90mm opening. The reason they throw a code, is with the larger diameter opening, to get the same amount of air to pass through the intake, it now moves much slower. Because it is moving slower through the MAF sensor, the car thinks not enough air is getting though, hence the to lean. Your power gain is still the same, you are only gaing power from less restictive inlet path. None of these setups are forcing the air in, so its only that your engine can suck air in easier.

Either type setup, your gaining 5-10 from the intake making it easier to breath. The rest of the power your getting from the tune. The intakes with the 90mm just happen to need a tune to make the factory maf function to the new flow rates. But the trade is they also shine when you start adding more mods that increas the flow through the motor.

IMHO, have your friend send that BBK back (and I used to run it,) Get one of the intakes with the 90mm inlets, and get it from Bama with a SCT and tunes. If you get one of the race tunes, not only does it give a good increase in power, but he does amazing things with maping the throttle and the response is just amazing.